The first participant in a clinical trial designed to evaluate the effectiveness of smoking marijuana to treat PTSD in veterans was given cannabis on Monday, according to the organization conducting the study.

The study is the first such trial to evaluate the safety and effectiveness of using marijuana to manage symptoms of post traumatic stress disorder in U.S. veterans, officials with the Multidisciplinary Association for Psychedelic Studies said in a release on Tuesday.

MAPS is a California-based non-profit research organization focused on "the careful uses" of marijuana, according to its website. The study is funded by a $2 million grant from the Colorado Department of Public Health and Environment.

The study will look at the safety and effectiveness of four separate levels of marijuana potency in 76 veterans. It will provide data on marijuana dosing, composition and side effects, and the potential benefits of using pot to treat PTSD.

The data will be intended for clinicians and legislators considering marijuana as a potential treatment for PTSD.

The first veteran to participate in the study received the marijuana on Monday at the Scottsdale Research Institute in Phoenix, Arizona, the release stated.

The study is taking place in two locations: in Phoenix, led by Dr. Sue Sisley, and at Johns Hopkins University in Baltimore, led by Ryan Vandrey.

The study is recruiting adult military veterans who have experienced trauma during military service. Screening for volunteers began in January.

Volunteers will complete 17 outpatient visits to one of the study location clinics in a 12-week period, with a follow-up visit in six months.

Veterans interested in volunteering for the clinical trial may email arizona@marijuanasites.org for the Phoenix location or call (410) 550-0050 to reach the Baltimore location.

"As this is the first placebo-controlled trial of cannabis for PTSD, we are breaking important ground needed to identify improved treatment options for veterans with PTSD," said Marcel Bonn-Miller of the University of Pennsylvania’s Perelman School of Medicine, in the release. Bonn-Miller is overseeing the project at the two study sites.

The research received approval in early 2014 from the federal Health and Human Services Department and was to get underway at the University of Arizona and other locations. The program was delayed after the school in Tucson terminated Sisley’s contract, Military Times reported in January 2015.

Sisley and MAPS worked for more than four years to develop the study protocol and win federal approval.